Heretofore, some rotors to be used in a rotary machine are configured such that a core made of an assembly of magnetic steel sheets laminated is fixed to a rotation transmitting member. To appropriately transmit rotation of the rotation transmitting member to the core, such configuration needs reliable fixation between the core and the rotation transmitting member. The rotation transmitting member is for example a shaft for a rotor of an inner-rotor type rotary machine. It is necessary to prevent all of the rotation between the steel sheets constituting the core, the axial rotation between the core and the shaft, and the sliding of the core in the axial direction of the shaft. For preventing the rotation between the steel sheets, for instance, it is well known that the steel sheets are slightly bent (see Patent Literatures 1 and 2).
For preventing the rotation between the core and the shaft, it is known that a key and a key groove, both being engageable with each other, are formed in the core and the shaft respectively. For preventing the sliding of the core in the axial direction of the shaft, further, it is known that plate members are placed in contact with both ends of the laminated steel sheets in the laminating direction and the plate members are bent (swaged) to the shaft to thereby hold and fix the laminated sheets between the plate members. It is also known that a shaft is provided with a flange at one end side in the axial direction to fix the steel sheets assembly (see Patent Literature 1 for example).
Furthermore, another technique is also known in which the steel sheets assembly is fitted on an outer periphery of a core back and fixed to a shaft through this core back (see Patent Literature 2 for example). In this technique, the core back is fixed to the shaft. The core back is formed with a plurality of holes and each sheet is fixed to the core back through the holes by laser welding. Accordingly, this configuration is provided with a space or clearance enough for insertion of a laser head between the core back and the shaft.